1. Field of the Invention
The present invention relates to a forming method of a resist pattern with a chemically-amplified resist and a manufacturing method of a thin-film magnetic head with the resist pattern formed with this method.
2. Description of the Related Art
In case of manufacturing thin-film elements such as thin-film magnetic heads, semiconductor elements, or micro devices, a process of forming a photo resist pattern is frequently performed.
In this case, the photo resist pattern could be formed on steps formed on a substrate. Especially, in an integrated process, for example, a perpendicular magnetic head, there is a case of forming the resist pattern so as to cover a magnetic pole having the steps whose gradient angle is equal to 90 degrees or more. In case of forming a positive type photo resist pattern, the steps make shade portions, therefore sufficient exposure is not performed in the shade portions. In forming the positive type photo resist pattern, the resist pattern is formed by eliminating the exposed portion with development so that the unexposed portion is residual without being eliminated with the development. If the portion which should be exposed is not exposed, a resist residue could occur at this portion. The resist residue causes a problem since this portion does not apply plating well in a latter process.
For example, we consider forming the resist pattern on the step formed on the substrate as FIG. 1a. In the step, gradient angle θ is 90 degrees or more. Here, the angle θ is a supplementary angle of an angle φ between a wall surface 10 and a surface 11 of a layer containing the step. The resist pattern is formed by coating the resist on the step, exposing the resist via a reticle, etc., and then developing the resist. In the case of forming the resist pattern 12 as in FIG. 1b, a ledge of the resist occur (a resist residue 13) at the portion among the wall surface 10, the surface 11 of the layer containing the step, and the resist pattern 12. In FIG. 1b, a darker-shaded area is the resist residue 13. Since the gradient angle θ is equal to 90 degrees or more, exposing light is shielded by the step. For this reason, an unexposed portion is made. In the case of a plating resist pattern formed above, the tracing of the portion of resist residue 13 causes a problem that a desired plating is not formed.